The invention concerns a lancet comprising a lancet needle with a tip and a lancet body which completely surrounds at least the tip region of the lancet needle. In addition the invention concerns a lancet comprising a lancet needle with a tip and a hollow body which surrounds at least the tip of the lancet needle. The invention also concerns a lancet magazine containing at least two lancets which each contain a lancet needle with a tip and which are each accommodated in individual chambers of the lancet magazine that are independent of one another, each chamber having at least one opening through which the tip of the lancet needle can emerge. Finally the invention concerns the use of an elastic material as a component of a lancet or lancet magazine.
The examination of blood samples in clinical diagnostics enables an early and reliable detection of pathological states and a specific and well-founded monitoring of physical conditions. Medical blood diagnostics always requires the collection of a blood sample from the individual to be examined. Whereas several milliliters of blood are often collected for the analysis of a person to be examined by venepuncture in hospitals and by physicians in private practice in order to carry out many laboratory tests, nowadays a few microliters of blood are usually sufficient for individual analyses of only one parameter. Such small amounts of blood do not require venepuncture. On the contrary, it is sufficient to obtain blood by pushing a sterile sharp lancet through the skin e.g. into the finger pad or earlobe of the person to be examined in order to collect a few microliters of blood for the analysis. This method is particularly suitable when it is possible to carry out the analysis of the blood sample immediately after blood collection.
Lancets and corresponding devices (so-called blood collection instruments, blood lancet devices or, as they are referred to in the following, lancing devices) which enable a substantially pain-free and reproducible blood collection are available especially in the so-called home-monitoring field i.e. where medical laymen themselves carry out simple analyses of the blood, especially for the regular blood withdrawal by diabetics which has to be carried out several times daily to monitor the blood glucose concentration. Furthermore the use of lancets with lancing devices is intended to lower the psychological barrier to piercing one's own body which is particularly important for children that suffer from diabetes and depend on regular blood glucose tests. Examples of lancets and lancing devices are the commercially available devices (lancing devices) and lancets: Glucolet® from the Bayer AG Company and Softclix® from Roche Diagnostics GmbH. Such lancets and devices (lancing devices) are for example the subject matter of WO-A 98/48695, EP-A 0 565970, U.S. Pat. No. 4,442,836 or U.S. Pat. No. 5,554,166.
The lancets of the prior art usually have a metal lancet needle with a tip which may be optionally sharpened. In many embodiments a plastic lancet body made of a rigid injection-mouldable material is injected onto the lancet needle to facilitate the handling of the lancet and optionally for its attachment in a lancing device. In the unused state the tip of the lancet needle is surrounded by a protective sheath to ensure its sterility. This sheath is usually composed of the same rigid material as the actual lancet body and then usually forms a single unit with this. The protective sheath can be separated from the lancet body and removed from the tip of the lancet needle before using the lancet. A predetermined breaking point is located between the lancet body and protective sheath for this purpose. After using the lancet, the tip of the lancet needle is unprotected and is thus a potential source of injury to the user and possibly other persons.
In order to avoid accidental injury on a used lancet needle, it is usually recommended that the users insert the tip of the lancet needle after use into the previously removed protective sheath. However, experience shows that not all users follow this advice and hence a large number of used lancets with unprotected tips are discarded. U.S. Pat. No. 5,304,192 and WO-A 96/02189 propose lancets as a solution to this problem in which the tip of the lancet needle can be pushed or pulled into the lancet body after use. Since in these cases the lancet body is manufactured from a non-elastic, substantially rigid or stiff material, the tip of the lancet needle, although it is concealed in the lancet body, is not completely hygienically protected because a channel remains in the material of the lancet body via which the lancet tip is in contact with the surroundings.
In the present commercially available systems the lancets are usually provided in a loose form for use in lancing devices. For each lancing process the user manually removes a lancet from a pack, for example a cardboard box or a tube containing a plurality of lancets which are usually in a disordered arrangement and loosely packed. Subsequently the lancing device is prepared for receiving the lancet by for example unscrewing or pulling off a protective cap to expose the lancet holder of the lancing device. The lancet holder is used to receive the lancets. It also guides the lancet during the actual lancing process. The lancet removed from the pack is manually inserted into the lancet holder of the lancing device and fixed there. Then the protective sheath that surrounds the lancet tip and protects the tip as well as the user has to be manually removed from the lancet. Subsequently the lancing device is sealed again with its protective cap. The protective cap ensures that the lancet is no longer accessible from outside. It usually has an opening through which the lancet tip can pass during the actual lancing process. Finally the lancing device is tensioned and is available for the lancing process to collect blood.
The many manual operating steps required for conventional lancet systems (lancet and lancing device) are felt to be disadvantageous by the user and are particularly problematic when perception is limited in a hypoglycaemic state. Moreover, the user is not prevented from using a once inserted lancet several times for lancing and collecting blood. This is risky for hygienic reasons especially when the lancet system is used by more than one person which for example may be the case in doctor's practices or hospitals. On the other hand, the repeated use of lancets also leads to increasing pain for the user since the lancets are designed for single use and rapidly become blunt when used several times. Furthermore with the lancing devices and lancets of the prior art there is a risk that lancing devices will be used with lancets that do not fit i.e. with lancets that are not suitable for a particular type of lancing device and thus lead to sub-optimal lancing results (reproducibility, lack of pain, amount of blood collected) or that the lancets are inserted incorrectly into the lancing devices. Furthermore a user can be accidentally injured when the lancets and lancing devices are used improperly.
There have therefore be no lack of attempts to eliminate the said disadvantages. Lancing devices are known from U.S. Pat. No. 5,514,152, U.S. Pat. No. 5,152,775, WO-A 98/14125, U.S. Pat. No. 3,030,959, U.S. Pat. No. 4,794,926 and U.S. Pat. No. 5,035,704 which store several lancets and can use these individually and in succession for lancing processes. After the lancing process the lancets can be removed individually from the device. However, these systems with lancet storage do not solve the above-mentioned problems of used lancets anymore than the systems which manually have to be individually loaded with lancets.